Magic -- taking the step to leave is hard.
One quote on another thread recently was that it is like inching along a diving board and one day (dont know why, dont know when) you will jump.
You are staying where you are due to FOG (fear, obligation, guilt) which is a trap and not a valid reason for anything.
Do some practical, theoretical, research to see what is possible if you separate. Do you own or rent? Look at properties online. Look at your finances - build in child tax credits, child benefit, maintenance, reduction in council tax etc.
Do some day dreaming - what would it be like to live with only your DD -- not walking on egg shells, going on holiday, giving her more positive input as you have more to give as you are not distracted and drained by his nonsense.
You dont have to justify your aversion to his habit to anyone if your social circle think it is OK. Just say you are moving on. You dont need anyones approval to separate - you dont need to quantify his use to reach a threshold that is unacceptable to others.....it is what it does to you and your DD that is important.
As PP said - look ahead - you DD will be impacted by his unreasonable mood swings and emotional detachment - she will be at risk of teenage issues.
She deserves better than this even if you think that you dont.